Ok that's fine it's a joke or whatever, the fact you aren't denying that these characters are boobs and have no substance other than BIG B0O0OOBSSS.
It's a porn game so I guess it doesn't really matter right?
You'd get a lot more insight by actually trying it, rather than making snap judgements based on what's visible without actually touching on the content. Something about judging a book by its cover and all that.
You might be pleasantly surprised to find there's more substance than just what you're focusing on. In my experience, there are more than a few games with a theme or focus that's unmistakably on the mature side, but that are relatively deep and well-written. Then again, I'm just a random commenter on the internet; my word's not worth much, so you may as well find out firsthand instead, right?